<style>
</style>
<div class="login-register">
    <ul><li class="active">登录</li><li>注册</li></ul>
    <div class="cont">
        <div class="sign-in">
            <form>
                用户名：<input type="text" id="in-username" value=""><br>
                密码：<input type="text" id="in-password"><br>
                <input type="button" value="登录" id="sign-in-btn">
                <input type="button" value="去注册" id="go-up-btn">
            </form>
        </div>
        <div class="sign-up">
            <form>
                用户名：<input type="text" id="up-username" value=""><br>
                密码：<input type="text" id="up-password"><br>
                <input type="button" value="注册" id="sign-up-btn">
                <input type="button" value="去登录" id="go-in-btn">
            </form>
        </div>
    </div>
</div>